Common Grammatical Errors

Some Basic Concepts

By definition, a sentence has the following properties:
it contains a subject
it contains a verb
it expresses a complete thought

E.g., the sentence "Japan prospers" has a subject: "Japan"; a verb: "prospers"; and it conveys a complete thought or idea that makes sense.

Most sentences also have an object (receiver of the action); e.g., in the sentence "John kicked the ball," the object is "the ball."

Run-on Sentences (fused sentences)

Incorrect usage	Correct usage	Explanation
I jogged every day I wanted to get fit.	I jogged every day, for I wanted to get fit. I jogged every day; I wanted to get fit. I jogged every day. I wanted to get fit. Since I wanted to get fit, I jogged every day. Trying to get fit, I jogged every day.	Run-on sentences occur when two main clauses have no punctuation between them.

Comma Faults (comma splices)

Incorrect usage	Correct usage	Explanation
I jogged every day, I wanted to get fit.	I jogged every day, for I wanted to get fit. I jogged every day; I wanted to get fit. I jogged every day. I wanted to get fit. Since I wanted to get fit, I jogged every day. Trying to get fit, I jogged every day.	Comma faults occur when two main clauses are joined by only a comma.

Sentence Fragments

Incorrect usage	Correct usage	Explanation
Joe can balance a glass of water on his head. Without spilling a drop.	Joe can balance a glass of water on his head without spilling a drop.	A sentence must have a subject and a verb.

Faulty Subordination

Incorrect usage	Correct usage	Explanation
I gazed out of the bus window, noticing a person getting mugged.	Gazing out of the bus window, I noticed a person getting mugged.	Place what you want to emphasize in the main clause, not the subordinate clause. Here the mugging should be emphasized and so should be in the main clause.

Errors in Subject-Verb Agreement

Rule:The verb should agree with the subject in terms of number (singular or plural) and person (first, second, or third).

Incorrect usage	Correct usage	Explanation
There is no books.	There are no books.	The subject books is plural; therefore, the verb should be plural (i.e. are).
She like music.	She likes music.	The subject she is in the second person, and is singular; therefore, the verb should also be in the second person, and be singular (i.e.likes).
Neither Tom nor Harry were there.	Neither Tom nor Harry was there.	"Harry" is singular, so the verb should be also.
Neither Tom nor the others was there.	Neither Tom nor the others were there.	"Others" is plural, so the verb should be also.
All of the team were there.	All of the team was there.	"Team" is singular, so the verb should be also.
All the players was present.	All the players were present.	"Players" is plural, so the verb should be also.
There are a variety of books.	There is a variety of books.	"Variety" is singular.
	There is a lot of birds here or there are a lot of birds here.	Both are correct. The first is correct since "lot" is singular. The second is correct because it is gaining acceptance through popular use.
Here is wealth and beauty.	Here are wealth and beauty.	"Wealth and beauty" is plural.
She is one of the best doctors who has graduated from here.	She is one of the best doctors who have graduated from here.	"Doctors" is plural, so the verb should be also (i.e. "have").
"I forget" or "I forgot".	I've forgotten.	Note that "I often forget" and "I forgot my umbrella yesterday" are correct.

Errors in Noun-Pronoun Agreement

Rule:Pronouns should agree with their nouns in terms of number (singular or plural), person (first, second, or third), and gender (masculine or feminine).

Incorrect usage	Correct usage	Explanation
Did everyone remember their assignment?	Did everyone remember his assignment?	Everyone is singular, so the pronoun should be as well.
It was them who called.	It was they who called.	The nominative case (I, you, he, she, it, we, you, they, who) is used following some form of the verb to be.
If I were him, I would go.	If I were he, I would go.	As above.
It is me.	It is I.	As above.
Whom will succeed?	Who will succeed?	A simple rule-of-thumb is to use "who" when "he" would also make sense; and use "whom" when "him" would also make sense (e.g. "Him will succeed" does not sound right, while "he will succeed" does).
Who did you give it to?	Whom did you give it to?	As above. "You gave it to he" does not sound right, while "you gave it to him" does. Thus, use "whom".
It belongs to he and I.	It belongs to him and me.	The objective case of pronoun (i.e. me, you, him, her, it, us, you, them, whom) is used as the object of a preposition, such as "to".
Sam hired he.	Sam hired him.	The objective case of pronoun (i.e. me, you, him, her, it, us, you, them, whom) is used as the object of a verb.
He is as busy as me.	He is as busy as I.	Try stretching the sentence out: "He is as busy as I am busy, not "he is as busy as me am busy."
He was in the same class as us.	He was in the same class as we.	Try stretching the sentence out: "He was in the same class as we were in."
I trust Bob more than he.	I trust Bob more than him.	Try stretching the sentence out: "I trust Bob more than I trust him."
Now skate without me helping you.	Now skate without my helping you.	Use the possessive case of the pronoun (i.e. my, your, his, her, its, our, your, their, whose) in sentences like this.

Dangling Modifiers

Rule:Avoid dangling modifiers (i.e. adjectives or adverbs that do not refer to the noun or pronoun they are intended to refer to).

Incorrect usage	Correct usage	Explanation
While walking in the garden, Bob arrived.	While I was walking in the garden, Bob arrived.	The modifying phrase "while walking in the garden" does not refer to a particular noun or pronoun (i.e. it dangles).
After watching the movie, pizza was eaten.	After watching the movie, we ate pizza.	As above.

Misplaced Modifiers

Incorrect usage	Correct usage	Explanation
I could almost run all the way up the hill.	I could run almost all the way up the hill.	The first sentence does not mean what it is intended to mean. The modifier "almost" is misplaced.
I only want one.	I want only one.	Same as above.

"Were"to be used in the Subjunctive Mood

Rule:Use "were" in the subjunctive mood, i.e. when expressing a wish, regret, or a condition that does not exist.

Incorrect usage	Correct usage	Explanation
If I was taller, I would be richer.	If I were taller, I would be richer.	This sentence is in the subjunctive mood.
He treats him as if he is a child.	He treats him as if he were a child.	As above.

That, Which, and Who

Incorrect usage	Correct usage	Explanation
This is the book which he wrote.	This is the book that he wrote.	When commas are not used, use "that".
This book, that is written by Bob, is clear and concise.	This book, which is written by Bob, is clear and concise.	When commas are used, use "which".
He is the person that wrote the book.	He is the person who wrote the book.	For persons, use "who". Do not use "who" for animals.
The President, which is an avid golfer, was on the course.	The President, who is an avid golfer, was on the course.	For persons, use "who", even when commas are used.

Note:Often the above pronouns can be omitted making a sentence more concise. Thus:

This is the book he wrote. ("That" is implied.)
This book, written by Bob, is clear and concise.
He wrote the book.
The President, an avid golfer, was on the course.

Faulty Parallelism

Incorrect usage	Correct usage	Explanation
He has wealth, reputation, and is powerful.	He has wealth, reputation, and power.	Similar ideas should be expressed in grammatically similar ways.
Not only did the horse lose, but the leg of the jockey was broken.	Not only did the horse lose, but the jockey broke his leg.	Similar ideas should be expressed in grammatically similar ways.

Mixed Constructions

Incorrect usage	Correct usage	Explanation
He wondered whether she got his message?	He wondered whether she got his message.	Don't mix a statement with a question.
The reason is because I don't have enough money.	The reason is that I don't have enough money.	Don't mix two different sentence constructions.

Split Infinitives

Incorrect usage	Correct usage	Explanation
I need to mentally prepare.	I need to prepare mentally.	"To prepare" is an infinitive. Splitting infinitves with other words tends to be awkward.

Commas

Incorrect usage	Correct usage	Explanation
I have apples, oranges, peanut butter and jam.	I have apples, oranges, peanut butter, and jam.	Use a comma before the last item in a series to avoid any confusion.
The dog was wet cold and smelly.	The dog was wet, cold, and smelly.	Use commas to separate adjectives that could be joined with "and." You could say that "the dog was wet and cold and smelly."
Captain Smith is a seasoned, naval officer.	Captain Smith is a seasoned naval officer.	Don't use commas to separate adjectives that could not be joined with "and." It would be ridiculous to say that "Captain Smith is a seasoned and naval officer."
You stand in line, and I'll find a table.	You stand in line and I'll find a table.	Don't use a comma to set off clauses that are short or have the same subject. However, always use a comma before "for", "so," and "yet" to avoid confusion.

Semicolons

Incorrect usage	Correct usage	Explanation
The house is old, however, it is sound.	The house is old; however, it is sound. The house is old; it is, however, sound	Use a semicolon with a conjunctive adverb (e.g. nevertheless, however, otherwise, consequently, thus, therefore, meanwhile, moreover, furthermore).

Apostrophes

Correct usage	Explanation
Tom Jones' car broke down. Tom Jones's car broke down.	Since there is disagreement on which is correct, both are acceptable.
Tom Williams' car broke down. Tom Williams's car broke down.	Same as above.